Comparisons will inevitably be drawn between the source novel and the series but as I have neither read the book nor seen the series I watched this with no preconceptions or expectations, judging it on its own merits.

The plot is straightforward as it sees intelligence analyst and espionage veteran George Smiley (here played by Gary Oldman) forced out of semi-retirement to investigate and uncover a Soviet agent operating from within MI6. What follows is a myriad case of friendship, rivalry, deception, interrogation (both verbal and otherwise), love, betrayal, paranoia and conspiracy.

Set in 1973 the film manages to easily transport the viewer into the dark days of the Cold War and the Iron Curtain. Like films of that era ‘The Parallax View’, ‘The French Connection’ and ‘All the Presidents Men’ the screen is drained of colour. The early 1970s were bleak years indeed with the Vietnam war still raging, the energy crisis, the three day week and of course the threat of mutually assured mass destruction should the USA and USSR declare war on each other.

This is not a world of fast cars, casinos, tuxedos and a playboy lifestyle. This is a Britain that finds itself no longer a superpower and reduced to gathering intelligence for the Americans.

The exceptional cast that also includes ‘Sherlock’s’ Benedict Cumberbatch as Smiley’s assistant in the investigation Peter Guillam, Tom Hardy, Colin Firth, Mark Strong, Kathy Burke (on fine form), Stephen ‘Boardwalk Empire’ Graham, Ciaran Hinds, John Hurt and Toby Jones (and apologies to anyone I may have left out).

This is a veritable parade of British acting talent and everyone can take a bow as this film gripped me from start to finish and being a ‘talky’ film that is all down to individual performances and effort.

You see, what really shines is not just the attention to period detail (and believe me the research is all up there on the screen), nor the fact that everyone seems to be smoking, drinking booze or cups of tea and casting a suspicious eye over everyone, it is the believability of the raw emotions of the characters that makes this so special.

The danger for any film with such a well known cast is that instead of following the plot you can unsuspectingly find yourself ‘star spotting’ ‘oh look, it’s so and so’ fortunately the performances are so on the mark that I was totally engrossed and immersed in the story.

Most importantly you totally invest in the characters, you understand Guillam’s outrage after a tongue lashing and accusation from his superiors, you feel Smiley’s anger and hurt when he discovers his wife is having an affair. Ricki Tarr’s (Hardy) unauthorised involvement in a case whilst stationed abroad is understandable as is his resentment and mistrust towards his superiors.

While all this is going on the plot offers plenty of twists and unexpected developments to keep the viewer guessing as to the identity of the mole. When the secret is finally revealed it is done in such a way that you can’t help but smiling at the ingenuity and subtlety of it all.

This is espionage as it probably is in the real world. Author le Carre comes from an intelligence background and it shows. These are flesh and blood people who can feel love, hate and despair. It is a game of bluff and strategy and Oldman does a masterful job of portraying old pro Smiley as the enigmatic, underrated and overlooked spy.

Director Tomas Alfredson has managed to get the best out of a talented cast and has effortlessly captured a bygone era suffusing proceedings with palpable dark menace and suspicion.

This may not please le Carre devotes or fans of the Guinness version, but I was kept guessing and thoroughly entertained for the duration of this film which is all you can ask of a Cold War thriller.